JP6652474B2 - Electronic control unit - Google Patents

Description

  The present invention relates to an electronic control device, and more particularly to an electronic control device that electrically connects and fixes a metal base to which a circuit board is fixed and a ground region of the circuit board with fixing bolts.

  In the general industrial machine field, a mechanical system control element is driven by an electric motor. Recently, however, an electronic control device including a semiconductor element for controlling the rotation speed and rotation torque of the electric motor is electrically driven. A so-called electromechanical integrated type electric drive device that is integrated into a motor has begun to be adopted.

  As an example of an electromechanical integrated electric drive device, for example, in an electric power steering device of an automobile, a turning direction and a turning torque of a steering shaft which is turned by a driver operating a steering wheel are detected. The electric motor is driven so as to rotate in the same direction as the rotation direction of the steering shaft based on the detected value, and a steering assist torque is generated. In order to control the electric motor, an electronic control device is provided in the power steering device.

  2. Description of the Related Art As a conventional electric power steering device, for example, a device described in JP-A-2006-63619 (Patent Document 1) is known. Patent Literature 1 describes an electric power steering device including an electric motor unit and an electronic control device. The electric motor of the electric motor portion is housed in a motor housing having a cylindrical portion made of an aluminum alloy or the like, and the circuit board on which the electronic components of the electronic control device are mounted is connected to the output shaft in the axial direction of the motor housing. Is attached to a heat sink that functions as an ECU housing disposed on the opposite side. The circuit board attached to the heat sink includes a power supply circuit unit, a power conversion circuit unit having a power switching element such as a MOSFET or an IGBT for driving and controlling an electric motor, and a control circuit unit for controlling the power switching element. The output terminal of the switching element and the input terminal of the electric motor are electrically connected via a bus bar.

  The electronic control unit attached to the heat sink is supplied with power from a power supply via a connector case made of synthetic resin, and is supplied with detection signals such as an operation state from detection sensors. The connector case functions as a lid, is fixed so as to hermetically close the heat sink, and is fixed to the outer peripheral surface of the heat sink by fixing bolts.

  In addition, as an electric driving device in which an electronic control device is integrated, an electric brake, an electric hydraulic controller for various hydraulic controls, and the like are known.

JP-A-2006-63619

  By the way, in the electronic control device used for the electric power steering device described in Patent Document 1, various circuit boards constituting the electronic control device are fixed to a metal heat sink with fixing bolts. A ground area (copper foil pattern) for grounding is often formed on the board surface of the circuit board. In this case, the fixing bolt electrically connects the ground area of the circuit board and the heat sink. It must have a function to connect to For this reason, a metal bolt that enables electrical conduction is used as the fixing bolt.

  Also, in an installation place where a large amount of vehicle body vibration is generated, such as an electric power steering device of this type, the fixing bolt is loosened by vibration and the axial force is reduced, so that the circuit board is also vibrated by vibration. In this case, there is a possibility that the wiring connecting each substrate may be damaged. In the worst case, the fixing bolt may fall off.

  In order to prevent such fixing bolts from loosening or falling off, it is necessary to use fixing bolts having a special locking mechanism, which complicates the structure, increases the product unit price, and does not allow downsizing. Such a new problem arises.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a novel electronic control device that can securely prevent a fixing bolt from loosening and ensure electrical conduction between a circuit board and a metal base with a simple configuration.

  A feature of the present invention is that a distal end side exposed portion where a metal surface forming a fixing bolt is exposed is formed on a screw distal end side of the fixing bolt, and a part of a screw surface on a head side of the fixing bolt from the distal end exposed portion is formed. A coating for preventing loosening is applied to the surface of the circuit board, and the fixing part of the metal substrate is fixed by screwing the fixing bolt into place. The head of the fixing bolt is fixed to the ground area of the circuit board. Where the fixing bolt is secured to the mounting and fixing part by the locking part of the fixing bolt, and further, the exposed part on the distal end from the locking part of the fixing bolt is electrically connected to the mounting and fixing part. It is in.

  ADVANTAGE OF THE INVENTION According to this invention, since the front-end | tip exposed part of a fixing bolt is screwed and contacted with the attachment fixing part of a metal base, reliable electrical conduction can be ensured. Further, since the locking portion of the fixing bolt is screwed into the mounting fixing portion of the metal base, reliable locking can be ensured. Further, since the anti-loosening paint is only applied to a part of the screw surface of the fixing bolt and dried, the configuration is simplified. Therefore, the structure is not complicated and the increase in the unit price of the product can be suppressed, and the size can be further reduced.

It is a sectional view showing the partial enlarged section of the electronic control unit concerning an embodiment of the present invention. It is a front view showing the front of a fixing bolt used for an embodiment of the present invention. FIG. 3 is an enlarged sectional view of a locking portion formed on the fixing bolt of FIG. 2. FIG. 7 is a cross-sectional view illustrating a partially enlarged cross-section of an electronic control device according to a modified example of the embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments, and various modifications and application examples are included in the technical concept of the present invention. Is included in the range.

  Although the present embodiment is basically directed to an electric power steering device having a configuration as described in Patent Literature 1, the present invention is not limited to this, and can be applied to various electronic control devices. FIG. 1 shows an enlarged cross section of a fixed portion between a circuit board and a metal base of the electronic control device according to the present embodiment, FIG. 2 shows a front view of a fixing bolt used in the present embodiment, and FIG. 3 shows an enlarged cross section of a locking part formed on a fixing bolt.

  In FIG. 1, reference numeral 10 denotes a metal base made of aluminum or an aluminum alloy, and has a function of radiating heat generated in an electronic circuit of a circuit board to the outside. However, in the present embodiment, a heat dissipation function is provided, but a general metal case may be used. A concave portion 11 is formed in the metal base 10, and a power conversion path section 12 for controlling the electric motor is disposed in the concave portion 11.

  The power conversion circuit section 12 is mounted on a metal circuit board 13 made of aluminum or an aluminum alloy, and the metal circuit board 13 is fixed so as to be thermally connected to the metal base 10. Therefore, the heat generated in the power conversion circuit section 12 is transmitted to the metal base 10, and is radiated to the outside and the motor housing via the metal base 10.

  The metal base 10 is integrally formed with a mounting and fixing portion 14, and the mounting and fixing portion 14 extends perpendicularly to the surface of the metal circuit board 13 so as to stand away from the metal circuit board 13. . A bolt screw hole 15 is formed in the attachment fixing portion 14, and a fixing bolt described later is screwed and fixed. In the present embodiment, four mounting fixing portions 14 are formed, and a control circuit section 16 described later is held and fixed by the four mounting fixing portions 14. The mounting and fixing portion 14 has a function of fixing the circuit board and a function of grounding the circuit board.

  A glass epoxy circuit board 17 on which electronic components constituting the control circuit section 16 are mounted is attached to the tip of the attachment fixing section 14, and the glass epoxy circuit board 17 is mounted on the metal base 10 by fixing bolts 18. It is firmly fixed to the fixing part 14. The control circuit unit 16 and the power conversion circuit unit 12 are connected by a connector terminal 19, and a control signal generated by the control circuit unit 16 is supplied to the power conversion circuit unit 12 via the connector terminal 19, and the power conversion circuit The switching element of the section 12 is controlled.

  The fixing bolt 18 includes a head portion 18H and a screw portion 18S (see FIG. 2) integrally formed of stainless steel, and the screw portion 18S is formed as a "full screw". The screw portion 18S has a tip-side exposed portion 18M-F in which the tip-side metal surface of the bolt itself is exposed, and a locking portion 18R formed in a partial region between the tip-side exposed portion 18M-F and the head 18H. And a root-side exposed portion 18M-B formed between the locking portion 18R and the head portion 18H.

  Here, a loosening prevention paint is applied to the loosening prevention portion 18R and dried to form a loosening prevention region. This will be described with reference to FIGS.

  Therefore, when the glass epoxy circuit board 17 is mounted on the mounting portion 14 with the fixing bolt 18 so as to sandwich the glass epoxy circuit board 17, the head 18H of the fixing bolt 18 is electrically connected to the ground area formed on the glass epoxy circuit board 17. The tip-side exposed portions 18M-F of the fixing bolts 18 are electrically connected to the mounting and fixing portions 14 of the metal base 10.

  This ensures that the ground area of the glass epoxy circuit board 17 and the metal base 10 are electrically connected to each other. Further, the bolt screw formed on the mounting fixing part 14 of the metal base 10 by the locking part 18R of the fixing bolt 18 Since the frictional resistance between the mating hole 15 and the screw surface increases, the fixing bolt 18 can be prevented from loosening.

  2 and 3 show the detailed configuration of the fixing bolt 18. FIG. As described above, the fixing bolt 18 includes the head portion 18H and the screw portion 18S, and the screw portion 18S is formed as a “full screw”. The screw portion 18S has a tip-side exposed portion 18M-F in which the metal surface of the bolt itself is exposed on the tip side, and a locking portion 18R formed in a partial region between the tip-side exposed portion 18M-F and the head portion 18H. And a root-side exposed portion 18 </ b> M-B formed between the locking portion 18 </ b> R and the head 18 </ b> H and exposing the metal surface. Further, a flat washer 20 and a washer 21 are interposed between the head 18H and the root-side exposed portion 18M-B.

  The loosening preventing portion 18R is applied with a predetermined width of a synthetic resin loosening preventing paint and is subjected to a drying process. The anti-loosening paint has flexibility in a dry state. As shown in FIG. 3, a locking resin 23 made of a synthetic resin having adhesiveness, insulation and flexibility is applied to the valley between the threads 22 of the locking portion 18R.

  As the anti-loosening paint 23, for example, an epoxy resin paint mixed with a modifier for imparting flexibility can be used. In addition, since it is an epoxy resin paint, it has excellent adhesiveness to the surface of the screw thread 22 of the fixing bolt 18. Further, the formation range of the loosening prevention portion 18R may be determined between about 20% to 50% of the length (nominal length) of the screw portion 18S. Further, the formation position of the loosening prevention portion 18R is preferably near the center of the screw surface 18S.

  Here, what is important in forming the locking portion 18 </ b> R is that the distal end side exposed portion 18 </ b> M-F is always formed. For example, if the root-side exposed portion 18M-B is formed and the anti-loosening paint 23 is applied to the tip of the fixing bolt 18 in order to enhance the anti-loosening effect, the following problem occurs.

  That is, when the fixing bolt 18 is screwed into the bolt screwing hole 15 of the mounting and fixing portion 15, the anti-loosening paint 23 on the tip side of the fixing bolt 18 adheres to the screw surface of the bolt screwing hole 15, and the electrical connection is made. There is a possibility that an insulating function is provided. Therefore, the root-side exposed portion 18M-B formed on the side of the head 18H is insulated by the loosening prevention paint 23 attached to the threaded surface of the bolt screw hole 15, which may cause a state of poor conduction. is there.

  On the other hand, when the distal end side exposed portion 18M-F is formed on the distal end side of the fixing bolt 18 as in the present embodiment, the metal portion of the fixing bolt 18 and the mounting fixing portion 14 of the metal base 10 must be formed. The metal part is screwed. For this reason, conduction between the metal base 10 and the ground region of the glass epoxy circuit board 17 is ensured.

  Then, the glass epoxy circuit board 17 is fixed to the mounting fixing portion 14 as shown in FIG. 1 by using fixing bolts 18 having the configuration shown in FIG. In this case, the flat washer 20 provided on the fixing bolt 18 is pressed against the ground region of the glass epoxy circuit board 17 so that electrical connection between the ground region and the fixing bolt 18 is achieved.

  Further, since the distal end side exposed portion 18M-F is formed on the distal end side of the fixing bolt 18, the metal portion of the fixing bolt 18 and the metal portion of the mounting fixing portion 14 of the metal base 10 are always screwed together, and finally As a result, the metal base 10 and the ground area of the glass epoxy circuit board 17 are reliably connected to each other. Further, the frictional resistance between the screw surface of the bolt screw hole 15 formed in the attachment fixing portion 14 of the metal base 10 is increased by the loosening prevention portion 18R of the fixing bolt 18, so that the fixing bolt 18 is prevented from being loosened. Can be.

  Although the above-mentioned fixing bolt 18 is in the form of “full screw”, it may be in the form of “half screw”. In this case, too, the screw portion may be loosened with the distal end exposed portion 18M-F. If the stopper 18R is formed, the above-described functions and effects can be obtained. In the case of a "half screw", the root-side exposed portion 18M-B may be an unthreaded region.

  Furthermore, it is also possible to provide the front end side exposed portion 18M-F, and apply the anti-loosening paint 23 to the head 18H side. According to this, the locking region of the locking portion 18R is enlarged, so that the locking effect can be enhanced.

  Further, although the glass epoxy circuit board has been described as an example of the circuit board, a metal circuit board may be used. In this case, heat of the electronic circuit is radiated from the mounting and fixing portion to the metal base via the metal circuit board. Therefore, the mounting and fixing portion has a function of fixing the circuit board, a function of grounding the circuit board, and a function of radiating heat from the circuit board.

  As described above, according to the present embodiment, the distal end side exposed portion 18M-F is formed on the screw distal end side of the fixed bolt 18 so that the metal surface forming the fixing bolt 18 is exposed, and the distal end side exposed portion 18M-F is formed. A coating 23 for loosening prevention is applied to a part of the screw surface on the head 18H side of the fixing bolt 18 to form a locking part 18R which is dried, and the glass epoxy circuit board 17 and the metal base 10 form the fixing bolt 18. The head 18H of the fixing bolt 18 is electrically connected to the ground area of the glass epoxy circuit board 17 in a state of being screwed and fixed, and is loosened and fixed to the mounting fixing part 14 by the locking stopper 18R of the fixing bolt 18. The exposed portion 18M-F on the distal end of the fixing bolt 18 from the loosening prevention portion 18R is electrically connected to the mounting and fixing portion 14 of the metal base 10.

  According to this, since the distal end exposed portion 18M-F of the fixing bolt 18 is screwed into contact with the mounting fixing portion 14 of the metal base 10, reliable electrical conduction can be secured. In addition, since the locking portion of the fixing bolt is screwed into the metal base, reliable locking can be ensured. Further, since the anti-loosening paint is only applied to a part of the screw surface of the fixing bolt and dried, the configuration is simplified. Therefore, the structure for fixing the circuit board and the metal base and conducting between the ground area of the circuit board and the metal base is not complicated, so that it is possible to suppress an increase in product unit price, and it is possible to further reduce the size.

  Next, a modification of the present embodiment will be described with reference to FIG. Note that the same reference numerals as those shown in FIG. 1 indicate the same components, and a duplicate description will be omitted. The modification shown in FIG. 4 is different in that an electromagnetic noise shielding plate is provided between the mounting and fixing portion 14 and the glass epoxy circuit board 17.

  In FIG. 4, an iron cylinder 24 is sandwiched between the glass epoxy circuit board 17 and the mounting and fixing portion 14, and a collar 25 made of synthetic resin is provided so as to cover the cylinder 24 from the outer periphery. Further, since the cylinder 24 is connected to the electromagnetic noise shielding plate 26 made of iron, the electromagnetic noise shielding plate 26 is held between the glass epoxy circuit board 17 and the mounting and fixing portion 14.

  The electromagnetic noise shielding plate 26 has a function of electromagnetically shielding the power conversion circuit 13 and the control circuit 16. Therefore, the electromagnetic noise shielded by the electromagnetic noise shielding plate 26 flows from the mounting and fixing portion 14 to the metal base 10 via the cylinder 24. Also in this modification, the same operation and effect as those of the embodiment shown in FIG. 1 are obtained.

  As described above, according to the present invention, the distal end side exposed portion where the metal surface forming the fixing bolt is exposed is formed on the screw distal end side of the fixing bolt, and the screw surface of the head side of the fixing bolt from the distal end exposed portion is formed. A coating for loosening prevention is applied to a part of the area to form a loosening prevention part, and the fixing part of the circuit board and the metal base is fixed by screwing in the fixing bolt. Is electrically connected to the grounding area of the fixing bolt, and is fixed to the mounting fixed part by the locking part of the fixing bolt. Further, the tip end side exposed part from the locking part of the fixing bolt is electrically connected to the mounting fixing part. I have.

  According to this configuration, the exposed portion of the fixing bolt is screwed into contact with the mounting fixing portion of the metal base, so that reliable electrical conduction can be ensured. In addition, since the locking portion of the fixing bolt is screwed into the metal base, reliable locking can be ensured. Further, since the anti-loosening paint is only applied to a part of the screw surface of the fixing bolt and dried, the configuration is simplified. Therefore, the structure is not complicated and the increase in the unit price of the product can be suppressed, and the size can be further reduced.

  Note that the present invention is not limited to the above-described embodiment, and includes various modifications. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described above. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of one embodiment can be added to the configuration of another embodiment. Also, for a part of the configuration of each embodiment, it is possible to add, delete, or replace another configuration.

  DESCRIPTION OF SYMBOLS 10 ... Metal base, 11 ... recessed part, 12 ... Power conversion circuit, 13 ... Metal circuit board, 14 ... Mounting fixing part, 15 ... Bolt screw hole, 16 ... Control circuit, 17 ... Glass epoxy circuit board, 18 ... Fixing bolt , 18H: Head, 18M-F: Exposed end side, 18M-B: Rooted exposed part, 18R: Loosening prevention part, 19: Connector terminal, 20: Flat washer, 21: Washer, 22: Screw thread, 23 … Loose-prevention paint.

Claims (7)

A circuit board having a ground area formed thereon is mounted on a mounting portion formed on a metal base, and fixing bolts are screwed into the mounting portion so as to sandwich the circuit board, thereby fixing the circuit board to the mounting portion. The fixing bolt electrically connects the ground region and the mounting fixing portion,
A tip side exposed portion where a metal surface forming the fixing bolt is exposed is formed at a screw tip side of the fixing bolt, and a part of a screw surface on a head side of the fixing bolt from the tip side exposed portion is prevented from loosening. A coating is applied and dried to form a locking part, and the circuit board and the mounting fixing part are fixed by screwing in the fixing bolt, and the head of the fixing bolt is fixed to the ground area of the circuit board. Is electrically connected to the fixing bolt, and is secured to the mounting / fixing portion by the locking portion of the fixing bolt. Further, the tip-side exposed portion at the tip of the fixing bolt is more electrically connected to the mounting / fixing portion. An electronic control unit, which is connected to the electronic control unit. The electronic control device according to claim 1,
The electronic control device according to claim 1, wherein a length at which the locking portion is formed is set in a range of 20% to 50% with respect to a length of a screw surface of the fixing bolt. The electronic control device according to claim 2,
The electronic control device according to claim 1, wherein the locking portion is formed substantially at a center of a screw surface of the fixing bolt. The electronic control device according to claim 1,
An electronic control device, wherein the anti-loosening paint applied to the anti-loosening portion is a paint mainly composed of an epoxy resin paint. The electronic control device according to claim 4,
An electronic control device, wherein the anti-loosening paint applied to the anti-loosening portion contains a modifier for imparting flexibility to the epoxy resin paint. The electronic control device according to claim 1,
A concave portion is formed in the metal base, and a power conversion circuit portion is provided in the concave portion, and the power conversion circuit portion is fixed to the metal base via a metal circuit board,
An electronic control device, wherein a glass epoxy circuit board including a control circuit unit for controlling the power conversion circuit unit is fixed to the attachment fixing unit. The electronic control device according to claim 6,
An electromagnetic noise cutoff plate is disposed between the power conversion circuit unit and the control circuit unit, and the electromagnetic noise cutoff plate is sandwiched and held between the glass epoxy circuit board and the mounting fixing unit. Electronic control device.

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